perf tools: Add unit_number__scnprintf function

Add unit_number__scnprintf function to display size units and use it in
-m option info message.

Before:
  $ perf record -m 10M ls
  rounding mmap pages size to 16777216 bytes (4096 pages)
  ...

After:
  $ perf record -m 10M ls
  rounding mmap pages size to 16M (4096 pages)
  ...

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1483955520-29063-2-git-send-email-jolsa@kernel.org
[ Rename it to unit_number__scnprintf for consistency ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index a512f0c..1fa9b9d 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -96,6 +96,7 @@ int test__perf_hooks(int subtest);
 int test__clang(int subtest);
 const char *test__clang_subtest_get_desc(int subtest);
 int test__clang_subtest_get_nr(void);
+int test__unit_number__scnprint(int subtest);
 
 #if defined(__arm__) || defined(__aarch64__)
 #ifdef HAVE_DWARF_UNWIND_SUPPORT